Gear checking device



Feb. 16, 1954 F. A. LA FEMINA 2,669,028

GEAR CHECKING DEVICE Filed Oct, l2, 1945 2 Sheets-Sheet l ATTORNEY Patented Feb. 16, 1954 lllvlrlazng sfrArss PATENT OFFICE 2,669,028; GEAR. onEcKINc DEVICE Frank A. lLa Femina, New York, N. Y. Application October 12, 1945, Serial No. 622,108-

9 Claims;

(Grantedeunrler' This invention relatesv totesting devices and more` particularly to. a device for: checking the trueness. of gears.

An object of this invention is-.to provide novel means for checking gears. under actual running conditions.

Anothery object is to expedite the testing of gears;

A further object. is to provideV suchaccurate testingmeansfor'gearsthatthe need for lapping said-@gears for nal fit will be eliminated.`

Further-objects andV advantages. of' this invention,V as.welll-as.itsconstruction, arrangementand operation. will be'V apparent from the following description and; claims. iii-connection with the ac-. companying; drawings, in which,

liigure.l 1 is ay front. elevation of;v a` device embodying the present invention,

Figurei 2 is, an elevation, partly. in section, viewed f-rom the. right off Figure 1;,

Figure 3 is a cross-sectional plan', takensalong the line-3-3 of -Figure l,

Figure 4 isvaf cross-sectional elevation,l taken through thegear center; as indicatedfbyline; 4-4 of'. Figure 1.

The device of the present invention: comprises,

tliebase plate I2 that.v supports agearbeinginspectedl Under practiceor the invention, a set, Ozfgearsisvmounted ontheplateA I2 with the-gears;

oyathe `set .in meshing relationship. Oneof" the gears-of the 'setzis undervv inspection. The` other gearyisf.knowni to be accurately machined; and preterablyf constitutes a master.- gear, madeand used only for inspecting gears` that are. designed.

tot mesh with it.

Each gear is supportedtontheplate I21gby a mounting individual: to itself; themountingfins cluding a bearing. in which the gear rotates. The mounting serves toy locate its gear inpredeterminedgposition, relative ,toI thebase plate;- I 2; The

plate- I2 tllusnserves: as a=.base-. structure forwsups.

portngithe several gearsof the setgin predeter-l mined positions;` relative to: each other, and .prioon-venient datum -fo'rymeasuringthezloe each gear.` relative to: the plate,..by. this gea. relative; tof each; other; f

Each mounting isv suitableifor; the gear that it'. SQEPQIS, dferenbzkinds: fm0untngss being-1 providedfY tofaccommodategcertairr d-iierent;l` typesof searsfoifdierent searing..

One kind of mounting comprises the upright1 guiddposts- HL, attaehedftovthehasel tto-protect upwardly-therefrom; in; parallelzrelationshin. A@ bearing. or.:massen.illustratedfeenerallrfatflt:

` to; measures. the:- 1012211110.11;l Ofthe.; several:

Title 35, U. S. C odex (1952) sec. 266)y isdetachablyattached to the set of posts I0, and adjustablly positionable lengthwise thereof. Pur'- suanttorthe purpose, each bearing 49 comprises the bearing: housing I-(with the bracket members I'I. projecting laterally therefrom. The brackets Il are-splitat Eil, Fig; 2, and each includes-a set screw- 5'Ifor the bearing Sito loe-clamped to a set of posts. I0. A bushing- I'f is secured in each housing I6 by` means of setA screws I9, and is machined to a predetermined inside diameter thatr locates the` center of? the bearing 49' midway-'between the posts I0.

The bearing 491vis suspended" from the bracket comprisingv thecrcsspiece 2T, havingA wing members 28 for attaching the'loracket 2l to thepair of posts II).l 'Each wing member`28-is split at 54, and includes-the set screwy l for clamping it to a post IIL The bearing-49 is connected to its companiony bracket 27 VIcy means of the screw 29. The saddle or strap 30; that serves as the headl of the screw- 29'- and accordingly is xedly attached.

thereto; is attachedftothe'bearing 49 byV any suit.

able means; The screw 29 projects upwardlyy from the; bearing 49T; throughvthe bore- 5l ofthe cross piece 21Fig.' 4andthe thumb nut SI isl provided to traversev the,V screw 29.V longitudinally amount; offad'justment ofv the bearing E49 towards` Screw 29A is` or awayf'romthe cross piece 21. preferably a micrometer screw, to enable adjust,- ments to thebearing 49 to be read in increments of 0.001, andto enable fractions thereof to4 be estimated...

A mounting.,l0,1I I for a givenbearing sais attachedtorthe base plate I 2Av in any suitablemanner. The.linteferred.practice.of the disclosed em.- bodiment is toprovde the base platewith parallei T-slots I5;v4 that.. accommodate 'ii-bolts. I4 for.

clamping the base` II.. to the base plate I2. by.

means ci. nuts.. I3.v ThekeyWay tais. companion-r to the.-T-slots I 51,: and. is positionedl midway between the set of T-slots. The .keyway'331 and T- slots, I5 areprecisionmachined to-constitute a locatinggdevice..thatlocates the center of abear ing49 that .issupportedfbyamounting It, II pre-l cisely withreferencefto the top, surface vet of the plate l2..Y

The,.basef,-plate I2. isproyided with a plurality l of r sets f of-` T-slots,. and these.- areoriented iny the facel 60., oi. theA plate l2 disposed at a. predetermined.; angle; with: reference; to; each other.` In. the; disclosed.'l embodiment. there isthe; pair off 3 *-slots I5', Fig. 3, that are disposed at right angles to the T-slots I5. T-slot 33' is disposed midway between T-slots I5. T-slots I5 and I5 are available for an inspection set-up of a pair of gears that rotate in mesh on axes at right angles to each other. Most bevel gears and some helical gears come within this category, and are inspected with a set-up using a mounting I0, II for each gear of the gearing, respective mountings I0, II being attached to base I2 in rightangularly disposed sets of slots I5, 33 and I5', 33'.

For an inspection set-up of gears that rotate in mesh on parallel axes, a bearing mounting I0, II is provided for each gear of the set, the two mountings being attached to the base I2 in the same set of slots, either I5, 33 or I5', 33'. Such a set-up is used, for example, for spur gears, herringbone gears, and parallel helical gears.`

The device of the present invention is also adapted for inspection of either the worm or the gear of worm gearing, and a set-up for a gear train of worm gearing is illustrated in the drawing as one practical application of the invention. Gear 24 is a helical gear that rotates in mesh with the Worm 4I on axes at 90 with reference to each other. One object of the inspection is to determine the degree of accuracy of the helix angle.

In the example shown, the mounting for gear 24 provides two-bearing suspension, and twobearing mounts I0, II are employed. These are attached to the base plate I2 in the same set of slots I5, 33, as shown in Figs. 2 and 4, which operates to position the two bearings 49 in coaxial alignment. The gear 24 being mounted between the bearings 49, on shaft 2 I.

The shaft 2I is provided with the abutment shoulder 22, Figs. 2 and 4, for locating the gear 24 properly positioned in the gear train. In the example shown the adaptor plate 23 is provided to adapt the gear 24 to the shaft 2I, and the web 6I of the gear 24 is attached to the plate 23 by means of bolts 62. The adaptor plate 23 is held in abutting engagement with the shoulder 22 of shaft 2I by means of the spacer sleeve 65, the nut 25 being threaded to the shaft 2I for the purpose, and the washer 20 being interposed between the spacer sleeve 65 and the nut 25.

Bearing 49 at the left in Figs. 2 and 4 is located lengthwise of shaft 2I by its bushing I8 being held against shoulder 22 by means of locating collar 68. Set screw 26 secures locating collar 68 to shaft 2I. Bearing 49 at the right in Figs. 2 and 4 is located lengthwise of shaft 2| by its bushing I8 being positioned in engagement with washer 20.

The bearing 49 at the left in Fig. 4 is adjustably positioned lengthwise of the T-slots I5. In this manner the center plane 44 of the gear 24 is located coincident with the axis of the worm 4I. See Fig. 2. The preferred practice is to locate the center plane 44 of the gear 24 properly positioned relative to the center of the worm 4I, by using the machined face 45 of gear 24 and measuring its position with reference to the precisely machined Wall of cross-wise T-slot 33 of the plate I2 as a datum.

The base 32 is provided as a support for the worm 4I, and is mounted rotatable to swing the axis of the worm 4I out of 90 relationship with the axis of the gear 24 for determining the accuracy of the helix angle of the gear being inspected. Accordingly, the base 32 is not keyed in the T-slot 33'. Instead the base plate I2 is provided with the socket 10, precisely centered with reference to the intersection of the keyways 33 and T-slot 33'. Plug 1I ts the socket "I0, and

projects downwardly from the bottom surface of the base 32 into bearing engagement with the socket 10. Thereby the base 32 is located for the center of worm 4I to intersect the vertical center plane 44 of gear 24 at its intersection with the vertical center plane of bearings 43, and base 32 can be swivelled out of right angle relationship with the vertical center plane of bearings 49.

The wing brackets 38, projecting from the sides of the base 32, carry the T-bolts 36 that t in the arcuate T-slots 39 in the base I2, nuts 31 being operable for the T-bolts 36 to hold the base 32 at any adjusted position of rotation on the center of the plug 'II. See Fig. 3. Arcuate graduated scales 40 are embedded in the surface 6I) of the plate I2, to enable measurement of the amount that the base 32 is rotated out of right angle relationship with the keyway 33 and with the vertical center plane of bearings 49. T-slots 33', Fig. 2, are provided extending inwardly from the ends of the base I2 to intersect each with an arcuate T-slot 39 to enable the T-bolts 36 to be removed from the base plate I2 when the. base 32 is removed therefrom.

The worm 4I is mounted to rotate on the centers I4 and l5, respectively carried by center stocks 34 and 35. T-slot I8 is disposed longitudinally of the base 32, and T-bolts i3 are operable to clamp the center stocks 34 and 35 onto the base 32. Stocks 34 and 35 are independently adjustably positionable longitudinally of the T- slot 78. lThe stocks34 and 35 are adjustable t0- wards and away from each other to position centers 14 and l5 with respect to each other properly spaced to provide a bearing for the worm 4I, and

the stocks 34 and 35 are adjustably positionable uniformly longitudinally of the T-slot 'I8 to 1ocate the worm 4I for proper meshing engagement with the gear 24. Under the disclosed practice, the worm 4I is pressed on the arbor 42, which is bearinged on the centers 14 and I5 as shown.

Center I4 is a fixed center, i. e., it is xed in the center stock 34 by means of set screws 16, Fig. 1. Center 'I5 is movable into and out of bearing engagement with the arbor 42, by rotation of the hand knob 43.

The inspection set-up shown in the drawing can be used for inspecting either the gear 24 or the worm 4I of worm gearing, in either case the other member being a master gear that is known to be accurate. The master member is used in the inspection set-up for inspecting each of a manufacturing lot of gears to determine its accuracy and to determine that the machining setup continues to be accurate for the machining of subsequent pieces, or the inspection set-up may be used to inspect selected gears of a production lot to determine from time to time that the production set-up continues to be accurate.

The worm 4I is mounted in the inspection setup for practice of the present invention by inserting the plug 'II of the base 32 in the socket 'Ill of the base plate I2, and then clamping base 32 on the base plate I2 by means of the T-bolts 35.

The base 32 is adjustably rotated on the center of the plug 1l until it is positioned for the longitudinal axis of the worm 4I to be parallel with the keyway 33 as determined by the scales 40. This positions the axes of worm 4I and gear 24 at with reference to each other, scales 40 being graduated to indicate a zero reading accordingly.

The teeth of either the worm 4I or the gear 24 are blued before they are placed in mesh, the preferred practice being to blue the member that is being inspected. The' worinv 4 and ytheagear 24- arebrought -intormeshing engagement `by the set screws of the bearingsw49= andthe set screws-55 of thebracketsll first being released. This enables each bearing 49, together with its bracket 2l as a unit, to be slid longitudinally of its supporting posts l@ until meshing engagement between the gear 24 and the worm 4| is approached. The preferred practice is to then tighten the set screws 55 ofthe brackets 2'1 only, when the worm 4| and gear 24- are positioned nearly in smooth meshing engagement, and to complete their adjustment. into .desired meshing engagement micrometrically by operating of the thumb nuts 3|. y

VMicrometric adjustment of the bearings 49 is made by both thumb nuts 3| being operated until the worm 4| and gear 2d are in smooth meshing engagement with the desired .degree of back-lash. Care must be exercised to adjust both nuts- 3| uniformly, so that proper bearing alignment of the shaft 2| is maintained. A condition of proper bearing alignment exists when opposite ends of the shaft 2| are at the same height, and thisl is determinable by measurement using the surface 60 of the base plate I2 as a common datum.

Now the gearing is driven in mesh, for example vby rotating the arbor 42 manually. If the worm 4| is being inspected, examination of the wear of its bluing will determine how accurately its threads have been machined. If the gear 2d is being inspected, examination of the wear of its bluing will determine how accurately its teeth have been machined, and it will also determine if the gear is uniform circumferentially. The distance is measured between the axes of centers 14, and shaft 2|, using the surface Bt of the base plate l2 as a common datum, to determine that the gear being inspected is machined for center-to-center dimension of design specication. The distance between the axes of centers 14, 15 and shaft 2| is set to conform with centerto-center dimension of design specification to determine that the gear being inspected is machined for proper back-lash.

After the gears have been rotated in mesh, the bluing may appear non-uniform lengthwise of the teeth of gear 24 and widthwise of the gear, i. e., the bluing may be off-center with reference to the center plane 44 of the gear 24. This indicates that the gear being inspected is machined inaccurately to the helix angle of design specifications. The condition -is usually accompanied by the center-to-center distance between gears being greater than design specification. To determine the extent to which the helix angle is inaccurate, the base 32 is adjustably rotated on the center of the socket 'l until the bluing is symmetrically disposed with reference to the center plane All of the gear 24, the nuts 3| also being rotated to adjust the gearing for smooth meshing engagement. The graduated scales d0 can then be read to determine the extent of inaccuracy of the helix angle.

This present invention is simple to operate, is sturdy, and where the gears to be tested are not very large, it can be made in a size that will make portability feasible.

It is to be understood that various modifications and changes may be made in this invention without departing from the spirit and scope thereof as set forth in the appended claims.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental 6 purposes without. the payment.v of any royalties thereon or therefor- What is claimed is:

1. In a gear inspectionl device, a main base, parallel supporting vmeans arising from the main base, gear-shaft supportingl means detachably secured at right angles'to the'parallel supporting means` and adjustably positionable. along the height of the parallel supporting means, a fine adjustment bracket slidably mounted on the parallel 'supporting means abovethe gear-shaftsupporting means, screw-threaded means` between the bracket andthe gear shaft supporting means to vary and measure the vertical displacement of the gear-shaft supporting means, aswivel base pivotal-ly secured to the main base between the parallel supporting means, adjustable tailucenfrters. detachably secured .to the swivel base, and means for measuring the angular: displacement of the swivel base securedv to the. main base.

. 2. In a vgear .inspection device,l a main base, parallel supporting .means arising from parallel horizontal platforms adjustably secured to .the main base, gear-shaft supporting means detachably secured at right angles. tov the parallel supporting means and adjustably positionable along the height of the parallel supporting means, a fine adjustment bracket slidably mounted on the lparallel supporting means above the gear-shaft supporting means, screw-threaded means between the bracket and the gear shaft supporting means to vary and measure the vertical displacement of the gear -shaft supporting means, a swivel base pivotally secured to the main base between the parallel supporting means, adjustable tail centers detachably secured to the swivel base, and means for measuring the angular displacement of the swivel base secured to the main base.

3. In a device for inspecting gears or the like, a base plate comprising a datum surface describing a plane, a plurality of mountings each for supporting a gear of a set of gears on the base plate, each mounting comprising a bearing for its gear of the set, each mounting resting on the datum surface with the axis of its bearing parallel with the plane of the datum surface and comprising an attachment to secure the mounting to the base with the axis of its gear bearing located a predetermined distance away from the plane of the datum surface, one mounting comprising a guideway for its bearing directed away from the datum surface of the base for adjusting the position of its bearing towards and away from the datum surface, a securing device for the bearing of the mounting that embodies the guideway to hold the bearing in predetermined position of adjustment along the guideway.

4. In a device for inspecting gears and the like as dened in claim 3, the mounting that embodies the guideways comprising a traversing mechanism for traversing the bearing along the guide- Way.

5. In a device for inspecting gears or the like as dened in claim 4, the traversing mechanism including a measuring instrument for the linear distance that the bearing is adjusted along its guideway.

6. In a device for inspecting gears or the like as dened in claim 3, a second mounting comprising a pivot on an axis perpendicular to the plane of the datum surface of the base plate to rotate the axis of its gear bearing relative to the mounting to thereby adjust the relative angular relationship between the axes of the bearings of the several mountings.

'7. In a device for inspecting gears 'and the like as defined in claim 6, the mounting that embodies the pivot comprising a scale for indicating the relative angular displacement between-the axes of the bearings of the several mountings.

8. The method of inspecting gears that comprises mounting the several gears of a set of gears on a surface plate in position with referenceto each other to rotate in meshing engagement in accordance with design specifications of the dimensions of the several gears of the set, adjusting the positions of the gears relative to each other with reference to the surface of vthesurfaceplate into relative positions of smooth meshing engagement, and measuring the displacement of adjustment of each gear with reference to the surface of the surface plate to determine the magnitude of departure from dimensions of design specifications of a gear of the set.

9. In the method of claim 8 as applied to gears of the helicoidal type, rotating the gears of the y set with reference to each other on an axis perlpendicular to the surface of the surface plate into adjustment of smooth meshing enga-gement, measuring the angular displacement of the rotary adjustment between gears to' determine the magnitude of inaccuracy in the angle of the geometric curve of the teeth.

- FRANK A. LA FEMINA.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,444,526 Sauer Feb. 6, 1923 1,624,415 Logue Apr. 12, 1927 1,909,088 Bauer May 16, 1933 2,296,894 Bauer Sept. 29, 1942 2,348,712 Dahlerup May 16, 1944 2,369,477 Martin Feb. 13, 1945 2,447,445 Widen Aug. 17, 1948 n FOREIGN PATENTS Number Country Date l633,878 Germany Aug. 8, 1936 697,430 Germany Oct. 11, 1940 OTHER REFERENCES American Machinist, February 18, 1943, pp. Q7-98. i 

